Firstly, I'm still interested and following this thread :-)
If you want to do it right from the begining you definitely need a constitution. Check out what other clubs have, and also guidelines for an "incoporated society" can be helpful, though I dont recommend adding the "inc" its a lot of work!!
At a bare minimum you need a president, treasurer, secretary. (Though one person could be sec/tresurer) probably a good idea to have a couple other comittee members too.
Does the FNZAS have special requirements for member societies?